Stunting - meaning physical height that is too short for a child's age - and anemia - indicated by low levels of hemoglobin - are two important nutritional outcomes. For both of these outcomes, children and women living in South Asia have among the worst nutritional status in the world. This extreme malnutrition is South Asia has been a longstanding puzzle in the research literature, in part because children in South Asia are shorter, on average, than children in Sub-Saharan Africa, who are poorer, on average. Height and anemia are both important because they reflect a child's broader physical and cognitive development. Research efforts to explain these South Asian nutritional deficits and policy efforts to design programs to improve outcomes have typically focused in providing more or better food. However, it may be the case that these nutritional deficits in fact importantly result from a exceptional burden of disease. Sanitation is very bad in South Asia, specifically in India. More than half of all families in India defecate in the open without using a toilet or latrine, and most people in the world who do so live in India. This exposes children to germs from feces that stunt their growth, sap their energy, and may prevent absorption of key nutrients. We will apply econometric techniques to large health-related survey datasets from South Asia in order to test this hypothesis. First, we aim to estimate whether there is a causal effect of open defecation on reduced child growth, and how big any effect is. We will produce this estimate by looking at two waves of survey data about Indian villages, measured seven years apart. Did villages where sanitation improved by more also experience a larger average increase in the height of children born at the end of the period, relative to the height of children born at the beginning of the period? Because the data we will use contains detailed socioeconomic data, we will be able to verify that results are not driven by changes in wealth. Second, we will estimate whether open defecation reduces hemoglobin levels in women and children. We will use a similar statistical approach to study change over time in sanitation and anemia in regions of Nepal. Additionally we will study country-level averages in sanitation and hemoglobin levels to assess whether differences in open defecation can account for some part of average differences across countries in anemia. Not only will this study contribute to resolving important, longstanding research puzzles about malnutrition, the results will indicate whether improving sanitation - and not only providing food - should be a key part of programs and policies to improve nutritional outcomes.